1. Field of the Invention
The present invention generally relates to an actuator and, in particular, relates to one such actuator having a two ended actuator rod movable both longitudinally and transversely.
2. Background of the Invention
As used herein the phrase "two ended actuator rod" and the idiomatic variations thereof is generally taken to mean an actuator rod having both ends thereof available for connection to or contact with linkages, structural members, or the like. Accordingly, the phrase "one ended actuator rod" and the idiomatic variations thereof is generally taken to mean an actuator rod having only a single end available for connection to or contact with a linkage, a structural member, or the like.
Actuators, in general, are well known and readily available on the commercial market in many configurations. Typical of actuators having one ended actuator rods are those described hereinafter.
U.S. Pat. No. 4,912,343 entitled Electromagnetic Actuator and issued on Mar. 27, 1990 describes, inter alia, an angular actuator that exerts a force along a predetermined arc. In that arrangement, the housing and electromagnetic assembly is formed in the shape of the arc through which the actuator arm is to be rotated. Hence, the actuator rod can only move along the predetermined arc. Further, the actuator has only one end of the actuator rod available to be connected to a linkage.
U.S. Pat. No. 5,099,158 entitled Electromagnetic Actuator issued Mar. 24, 1992 describes an actuator wherein angular forces can be exerted through a predetermined arc. As shown therein, in order to accomplish such angular forces the linkage connecting to the control arm must either have a slotted opening so that a first assembly of the actuator can move linearly relative to another to a second assembly of the actuator or have the first assembly be formed in the predetermined arc and have the second assembly ride therealong.
U.S. Pat. No. 4,969,662 entitled Active Damping System For An Automobile Suspension, issued Nov. 13, 1990 describes an active damping system wherein there is one actuator rod associated with each wheel of the vehicle.
U.S. Pat. No. 5,162,767 entitled High Efficiency Solenoid, issued Nov. 10, 1992 describes a solenoid wherein the plunger, or actuator rod, has one end thereof available for connection to a device to be controlled.
U.S. Pat. No. 5,207,239 entitled Variable Gain Servo Assist, issued May 4, 1993 describes a hydraulic actuator. The actuator described is a unilateral device wherein only one end of an actuator rod is available for connection to the device to be controlled.
U.S. Pat. No. 5,222,714 entitled Electromagnetic Actuated Valve issued Jun. 29, 1993 describes an actuator that is designed for high frequency operation. The actuator discussed has a one ended actuator rod.
Further, actuators having two ended actuator rods are also known. For example, in U.S. Pat. No. 5,187,398 entitled Electromagnetic Actuator issued Feb. 6, 1993 an actuator having a rod that can be connected to devices at both ends of the rod is described. The rod can be either unitary or segmented. The rod is maintained in position by openings in the end caps of the actuator and beatings are provided at each end of the casing.
U.S. Pat. No. 5,231,336 entitled Actuator For Active Vibration Control, issued on Jul. 27, 1993, describes a two ended controllable actuator rod. The actuator, as described therein, is used for active vibration control and includes openings that have bearings for maintaining the actuator rod in a linear position. Hence, such an actuator is limited to applying forces that are axially aligned with the actuator rod.
U.S. Pat. No. 5,212,977 entitled Electromagnetic Re-Draw Sleeve Actuator, issued May 25, 1993, also describes an actuator wherein the force exerted by the actuator rod is coaxial with the coil of the magnet.
U.S. Pat. No. 4,892,328 entitled Electromagnetic Strut Assembly issued Jan. 9, 1990 describes an assembly for use in an active suspension system for controlling the orientation of the chassis of a motor vehicle relative to the frame of the vehicle. Therein, each wheel of the vehicle is provided with an actuator that is aligned with the strut associated with the wheel of the vehicle it is to control.
U.S. Pat. No. 4,998,441 entitled Force And Torque Measurement System, issued on Mar. 12, 1991 describes a system for measuring forces applied to a mass. The system described includes an apparatus for suspending a mass and includes actuators for responding to forces generated and for generating signals in response thereto.
Many of the actuators discussed and described in the above patents typically find application in the general field of automobile vibration dampening systems wherein each wheel of the automobile is provided with an actuator controlled dampening apparatus for independent suspension systems. However, there is another, significantly different, field wherein actuators, in general, have been used for controlling, or damping, vibrations. Specifically, actuators are useful in reducing the vibrations of elevator cars.
As well known, elevators are installed to ride along guide rails within an elevator shaft. During installation, the guide rails are usually installed in sections that are bolted together. These rails, particularly in tall buildings, can only be installed sufficiently straight at considerable cost. The rails' alignment deteriorates with time, particularly in newly constructed buildings. Rail misalignment tends to appear as a periodic bending related to floor spacing. As a result of such bends, the elevator riding along the bent rails on rollers is caused to vibrate when the bends are encountered by the rollers. Hence, the ride may be uncomfortable for passengers using the elevators.
As shown in U.S. Pat. No. 5,322,144 and related patents of assignee hereof, to reduce such vibrations active control may be used, typically utilizing accelerometer feedback. Such a system detects horizontal vibration of the elevator car and provides a control signal to a compensating mechanism to exert forces between the car and rail to reduce the vibrations. As shown at 44 and 50 of the Figures of European patent application publication 0467673A2, at 22 of the Figures of U.S. Pat. No. 5,294,757 and in U.S. Pat. No. 5,086,882, for example, an actuator is installed proximate each guide wheel and exerts a force thereagainst in response to a signal from a sensor.
Another approach to reducing, or damping, vibrations caused by irregularities in the guide rails is disclosed and discussed in U.S. patent application Ser. Nos. 668,544 and 668,546 both filed on Mar. 13, 1991 and assigned to the assignee hereof (see EPO Publication 0503972A2 corresponding thereto). Therein, the general approach to compensating for vibrations caused by irregularities along the guide mils includes the determination of the rail profile during a rail learning run of the car in the hoistway. This information is then used to control the rollers when the elevator is in service. As shown therein actuators are used to control the movement of springs that interconnect with the rollers.
Consequently, although some conventional actuators move angularly or can be linked to rotatable arms via a pivot arrangement, none of these actuators allow a longitudinally slidable actuator rod to independently move in the transverse direction such that a rotatable lever, or linkage, having a fixed pivot point can be rigidly affixed to each end of the actuator rod.